JP2004104090A - Method and apparatus for removing surface contaminant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe and highly efficient method for removing contaminants to clean the surface of a substrate of an electronic device, such as a semiconductor wafer, a glass substrate for LCD, and various goods, at room temperature in a short period of time. <P>SOLUTION: The method for removing the surface contaminant comprises the steps of contacting processing liquid, in which an ozone concentration of 100 ppm or more is dissolved in organic solvent in which the distribution coefficient with ozone in gaseous matter is 0.6 or more, to the contaminant surface of the object to be treated, and removing the contaminant on the surface of the object to be treated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for cleaning articles requiring removal of contaminants, and more particularly to a method for cleaning a substrate for an electronic device. More specifically, the present invention relates to the removal of an organic film such as a photoresist used for processing a semiconductor wafer or a liquid crystal substrate, and cleaning of organic contamination generated throughout the wafer process. . More broadly, the present invention relates to cleaning organic contamination of precision metal and glass workpieces.
[0002]
[Prior art]
The removal of the photoresist used for the microfabrication on the oxide film or the polysilicon film is usually performed using a mixture of sulfuric acid (3 or 4 volumes) and hydrogen peroxide (1 volume) (called piranha) for 110 days. A method of heating to １４０140 ° C. and immersing for 10 to 20 minutes is used. When high-concentration ion implantation is performed using a resist mask, the resist is deteriorated and cannot be removed by piranha treatment. Therefore, ashing using plasma-excited oxygen is widely used. However, ashing all of the photoresist leaves trace metal from the resist on the wafer surface and harmful devices to the wafer surface due to the high energy plasma. Therefore, ashing is performed while leaving the resist film, and thereafter, the resist is removed by piranha treatment. Attempts have been made to mix ozone instead of hydrogen peroxide in this piranha treatment, but because of the low solubility of ozone, a longer treatment is required for removal and it is rarely used.
[0003]
Recently, a resist removal method using ozone water has appeared. The solubility of ozone in water increases as the temperature decreases, and the amount of dissolved ozone reaches 70 to 100 ppm in ultrapure water at about 5 ° C. When the resist is removed with such low-temperature and high-concentration ozone water, a 800 nm-thick positive-type novolak resin-based photoresist film widely used in LSI manufacturing can be stripped in about 10 to 15 minutes. (Peeling rate: 70 to 80 nm / min).
Organic substances such as dioctyl phthalate (DOP), siloxanes, and hexamethyldisilazane (HMDS) contaminate the surface of silicon wafers and oxide films from the atmosphere in a clean room for semiconductor device production, which degrades device characteristics. It is known that the device yield is reduced.
[0004]
As a wet cleaning method for removing organic substances on a silicon wafer or an oxide film, the above-mentioned piranha treatment has been most effective. However, SO₄ ^2-Remains on the wafer and generates fine particles under the influence of the environmental atmosphere, which tends to cause haze. To remove this completely, usually SC-1 treatment (standard composition is NH₄OH: H₂O₂: H₂O = 1 volume: 1 volume: 5 volume) and the like. The SC-1 treatment alone has the effect of decomposing and removing organic substances, and the effect of removing fine particles has hitherto been the most effective. However, in SC-1, Fe, Al, Ca, Mg, Zn, Ni, and the like in the chemical liquid easily deposit on the wafer during cleaning, and it is difficult to control the cleanliness of the chemical liquid and the cleaning tank. Therefore, the SC-2 treatment (standard composition is HCl: H), which is considered to have excellent metal removing ability except for the chemical oxide film generated by the SC-1 treatment with rare HF.₂O₂: H₂(O = 1 volume: 1 volume: 6 volumes) is a common means of semiconductor cleaning, and is called an RCA method. Surface residual SO₄ ^2-Although a method of performing a large amount of heating water rinsing for a long time has been used to remove, the achievable cleanliness is inferior when the normal RCA method is followed.
[0005]
As a cleaning method for organically contaminated wafers, conventional treatments relying on piranha treatment are not satisfactory in terms of economy, productivity and safety. Ozone water has emerged as a new cleaning method to solve these problems. At room temperature, 20 to 30 ppm of ozone water can be obtained, so that the oxidizing power is used to remove organic contamination of the wafer.
[0006]
[Problems to be solved by the invention]
With the advancement of semiconductor devices, especially VLSI, reduction of organic contamination on the wafer surface is becoming more and more important. Until recently, there was no mention of surface organic carbon concentration in the roadmap published by the Semiconductor Industry Association of America. 1x10 was announced at the end of 1997¹⁴Atom / cm²Organic carbon concentration is allowed, but in 2009 this concentration was 1.8 × 10^ThirteenAtom / cm²Is in need. This cleanliness is, of course, necessary even after the resist is stripped. The piranha cleaning liquid is repeatedly used in terms of economy, but if the methyl silicon layer on the oxide film generated by the positive resist adhesive HMDS is to be removed to such a high cleanliness level, the piranha cleaning liquid deteriorated by repeated use. Then it becomes difficult, so the number of uses must be severely limited. Therefore, the use amount of sulfuric acid is increased, which not only deteriorates economic efficiency but also complicates wastewater treatment.
Since the removal of the resist on the metal film is damaged by a strong acid treatment, the film is damaged by using N-methylpyrrolidone (NMP) as a remover at about 70 ° C. for about 15 minutes. In this case, ultrapure water rinsing is performed after rinsing with an organic solvent such as isopropyl alcohol. This treatment requires a large amount of an organic solvent, is not desirable in terms of economy, and is expensive in wastewater treatment.
[0007]
Accordingly, although ozone water treatment is expected, semiconductor-grade high-purity ozone water is produced by absorbing high-purity gas containing ozone into ultrapure water. By the way, when a gas containing ozone is injected into a container containing a liquid, the concentration of ozone in the gas becomes C_G[Mg / L], the concentration of ozone in the saturated liquid_Lす る と [mg / L], distribution coefficient D = C_L/ C_GIt becomes. Here, in the case where the liquid is water, in a certain research example, D = 0.28 at 25 ° C., D = 0.28 at 20 ° C., and D = 0.47 at 5 ° C., which is a normal high purity. Since the ozone concentration obtained by the ozone gas generator is about 200 mg / L, the saturation concentration is calculated to be 40 ppm at 25 ° C. and 94 ppm at 5 ° C. In practice, as described above, a concentration slightly lower than this concentration can be obtained. Moreover, ozone is easily decomposed in water, and the maximum level of ozone in the ozone water washing tank cannot be maintained unless ozone gas is constantly circulated and ozone gas is injected. In addition, if there is an obstacle to the flow such as a wafer carrier in the cleaning tank, a portion where ozone is insufficient on the wafer surface is formed, and the resist peeling speed decreases. Even if the stripping speed of the resist itself is about 100 nm / min, it is twice as long as the processing time calculated from the stripping speed to completely remove the methyl silicon layer from all the wafers in the wafer carrier. Need more. That is, it takes 20 to 30 minutes to remove the 1 μm-thick resist film.
[0008]
According to the present invention, the immersion type resist stripping including the complete removal of the resist adhesive is shortened, and the carbon amount of the surface after the treatment is reduced to 10%.¹²Atom / cm²The present invention provides a cleaning method which can be reduced to the order of 1) and is effective as a photoresist removing method.
[0009]
The organic matter found in the largest amount on a wafer in a semiconductor clean room is usually DOP, which often exceeds 200 ng on a 6 ″ wafer surface. This DOP forms a fine spot-like oil film on the wafer surface. The contaminant particles adhered to the surface are strongly captured by the liquid film of the oil film, making it difficult to remove by cleaning, a phenomenon that is significantly more significant on the back surface of the wafer than on the front surface. This is because, in the device manufacturing process, the back surface of the wafer may be treated in contact with another material like a vacuum chuck, and since this material surface is usually lipophilic, it is contaminated with DOP or the like and transferred. In the semiconductor device manufacturing process, the back surface of a wafer may face the front surface of an adjacent wafer, and a large number of wafers may be processed at the same time. At this time, the influence of organic matter contamination and fine particle contamination on the back side reaches the device forming surface facing the surface, and it is known that if there is contamination by DOP or the like, the removal of metal contamination is hindered in the cleaning process. The adverse effects include metal contamination.
[0010]
Therefore, the present invention also provides a method of cleaning a substrate surface capable of strongly removing contaminant contaminants on the front and back surfaces of a wafer and removing contaminant metals. Further, since this organic contamination removal is extremely powerful and environmental pollution can be easily controlled, the present invention provides a cleaning method applicable to cleaning bodies other than electronic device substrates.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides a treatment in which ozone is dissolved in an organic solvent having a distribution coefficient of 0.6 or more in a gas on an organic solvent having a distribution coefficient of 0.6 or more on the surface of a treatment object to which contaminants are attached. It is an object of the present invention to provide a method for removing contaminants adhering to a surface, which comprises contacting a liquid to remove contaminants adhering to the surface of the object.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Further, according to a preferred embodiment of the present invention, a liquid film of the processing liquid is formed on the surface of the processing object to which the contaminant adheres, and the processing liquid is continuously or intermittently added to the liquid film. The method for removing contaminants adhering to a surface is characterized in that the surface of the object to be treated is brought into contact with the ozone-containing treatment liquid by supplying a liquid film and moving the liquid film.
[0013]
This is because a particular organic solvent such as acetic acid dissolves ozone about 10 times more than water, as described below, and the liquid film is also in an amount sufficient for the ozone therein to act on surface-attached contaminants. It depends. If the ozone concentration in the atmosphere in contact with the liquid film is higher than the equilibrium concentration with ozone in the liquid, the ozone easily diffuses into the liquid film and the ozone concentration of the liquid rises to near saturation in a short time.
[0014]
Therefore, the present invention, as another preferred embodiment of the above method, in an atmosphere containing ozone, a liquid film of the organic solvent is formed on the surface of the object to which the contaminant is attached, and the film is continuously or intermittently formed. The present invention provides a method for removing surface-attached contaminants, which comprises contacting the surface of an object to be treated with an ozone-containing treatment liquid by supplying a new solvent to the liquid film and moving the liquid of the film. is there.
[0015]
In the present invention, upon removal of the surface-attached contaminants, the ozone-containing organic solvent liquid after the removal treatment is united with the organic solvent for dissolving ozone, and supplied as a removal treatment liquid for the object to be treated. The present invention provides a processing method and an apparatus for circulating water. Non-polar organic solvents such as acetic acid are less likely to be decomposed by ozone. For example, acetic acid is one of the most stable substances to ozone in a common organic solvent, and has high solubility in ozone. This dissolved ozone has a strong reactivity with organic substances having an unsaturated bond and has not only a decomposing effect, but also a carboxylic acid or carbon dioxide gas which is finally stable to ozone if sufficient reaction time is obtained. Decomposes into water. That is, in this circulation process, purification necessary for the removal treatment is performed, and the life of the removal treatment liquid can be extended. The most characteristically effective treatment of the present invention is provided which is extremely economical.
[0016]
The supply of the organic solvent liquid may be performed by spraying the liquid, and in this case, the movement of the liquid on the membrane may be caused to flow down or by centrifugal force. This liquid supply may be performed by liquefying the vapor generated from the heated liquid on the surface of the object to be cooled.In this case, the contaminant is removed by the vapor cleaning mechanism by the flow of the condensate. Will be removed. The present invention also provides an apparatus for removing contaminants adhering to the surface of an object, in which the liquid film on the surface of the object is moved in a chamber into which ozone gas is introduced by supplying the organic solvent liquid.
[0017]
In the present invention, when the contaminants attached to the surface of the object to be treated are removed by the organic solvent, the organic solvent molecules are slightly adsorbed on the surface of the object to be treated. However, the adsorption amount is (10^Thirteen-10¹⁴) Atoms / cm²It will be a low level. This is because even though the organic solvent contained in the contacted solution is an organic substance, the molecule contains few carbon atoms and has an extremely high concentration of coexisting ozone. This is a feature of the present invention. In addition, the adhesion of the organic matter adsorbed to the object to be processed is weak, and the carbon concentration can be easily reduced to 10 by the oxidizing treatment.¹²Atom / cm²Can be further reduced to lower orders. The oxidizing treatment includes, for example, oxidizing cleaning such as alkali / hydrogen peroxide cleaning, or oxidizing treatment with ozone under irradiation of ultraviolet rays of 184.9 nm and 253.7 nm. Further, when the surface of the object to be processed is made of a silicon oxide film, the adsorbed molecules can be removed to a carbon concentration level close to this by a slight peeling of the surface layer by dilute hydrofluoric acid.
[0018]
The organic solvent used in the present invention and having a partition coefficient with ozone in the gas of 0.6 or more is generally a non-polar organic solvent. The partition coefficient (D) is the partition coefficient of ozone between the organic solvent in the liquid phase in the standard state and the inert gas in the gas phase in contact with the organic solvent. That is,
D = saturated ozone concentration in organic solvent (mg / L) / equilibrium ozone concentration in gas (mg / L)
Indicated by
The partition coefficient of the organic solvent used in the present invention is preferably 1.0 or more, more preferably 1.5 or more, and further preferably 2.0 or more.
Any organic solvent having a partition coefficient with ozone in a gas of 0.6 or more can be used in the present invention without any particular limitation.
Formula: C_nH_{2n + 1}(COOH) a fatty acid represented by [n = 1 or an integer of 3 or 3] and dichloromethane, and particularly preferably the fatty acid. The fatty acids include acetic, propionic and butyric acids. These organic solvents can be used alone or in combination of two or more.
[0019]
In the present invention, the ozone concentration in the treatment liquid is 100 ppm or more, and more preferably 200 ppm or more. If the ozone concentration is less than 100 ppm, a sufficient pollutant removing action may not be obtained.
Since the fatty acid having a purity of 99.7% as described above has an approximate D of 1.9 at 25 ° C., an ozone liquid having a concentration approximately 10 times higher than that of pure water can be obtained. Therefore, it shows much higher pollutant removal ability than ozone water. The removal treatment may be immersion in an ozone solution, but it is preferable to use an organic solvent having a very small surface tension of 30 dyn / cm or less for treatment with the liquid film. The liquid easily spreads like a film over the entire surface of the object. Here, when the liquid moves, the surface contaminants acted on by the liquid also move at the same time, and efficient removal progresses. Also, the fine particles caught by the attached organic matter are easily removed because the organic matter dissolves in the liquid having a small surface tension and the liquid moves.
[0020]
Among these carboxylic acids, acetic acid with n = 1 is preferred, because it is cost-effective, a high-purity commercial product is easily available, and there is almost no problem in terms of toxicity. Although the melting point is 16 ° C., it is difficult to handle. However, there is no problem at a normal clean room temperature, and there is an advantage in recovery as described later. Since propionic acid with n = 2 has a melting point of −20 ° C., the action of the acid is weakened and the ozone can be processed at a high temperature and the low-temperature treatment can be performed on the object which is easily attacked by the acid. Butyric acid with n = 3 has a flash point of 72 ° C., which is about 20 ° C. higher than acetic acid or propionic acid. When it is desired to promote the reaction by heating, a treatment at about 70 ° C. can be performed without danger.
[0021]
Acetic acid containing a small amount of water is easier to dissolve inorganic salts, and has a lower coagulation temperature and is easier to use. A sufficiently high concentration ozone liquid can be obtained with a purity of 97% even at D = 1.7, 95% at D = 1.5, 90% at D = 1.3, and 85% at D = 1.1. Therefore, by adding water containing 5% by volume or less of an inorganic acid, especially hydrofluoric acid, to acetic acid, metal contaminants can be removed well at the same time. Since such a high D value can be obtained, when ozone gas obtained by a high-purity ozone gas generator is bubbled from a large number of micropores into acetic acid having a purity of 85% or more, even if the ozone concentration is about 100 mg / L, the ozone concentration can be easily obtained. Is 100 ppm or more, which can be provided to the present invention. When an ozone gas having an ozone concentration of 200 mg / L is used, the ozone concentration of the liquid becomes 200 ppm or more in several minutes.
If a glass filter is used as a divergent device for bubbling ozone gas, it can reach a concentration close to saturation in about 5 minutes, and the ozone concentration can be enhanced to nearly 400 ppm.
[0022]
When ozone gas having an ozone concentration of 300 mg / L is used, the ozone concentration of the liquid increases proportionally according to Henry's law. The ozone concentration in the liquid is 200 ppm or more, and the effect of the removal treatment of the present invention can be sufficiently obtained. The blue-violet color of the liquid having such an ozone concentration becomes extremely sharp. Since the color density has a positive correlation with the ozone concentration, the ozone concentration of the liquid can be controlled to a predetermined value by simple colorimetry.
[0023]
When it is not desired to use an acid or a water-soluble solvent which may cause rust after the treatment, dichloromethane is preferred as the organic solvent. When D = 2.0, ozone is hardly decomposed and toxicity is relatively low. Further, dichloromethane is suitable for carrying out the present invention by a steam cleaning mechanism, and when carried out with a mixed solution with acetic acid, the effect of removing contaminants is further enhanced.
[0024]
When a carboxylic acid is used in the present invention, a substrate for electronics industry is most suitable as the object to be processed. Adhered contaminants generated by adsorption from an environmental atmosphere or contact with an organic material can be easily removed. In particular, the positive type novolak resin resist on the silicon oxide film can be removed at a peeling rate of 1 μm / min to 6 μm / min, which is almost two orders of magnitude higher than the conventional one. In the case of dichloromethane, the object to be processed is preferably a metal processed product or a glass processed product, and a cleaned surface having a superior water droplet contact angle evaluation can be obtained as compared with the case of using alone for removing oily dirt, pitch and wax. The shape of the object to be processed is preferably a plate shape, but may be any shape as long as the movement of the liquid film is not largely uneven.
[0025]
In order to carry out the present invention, it is necessary to perform treatment in an airtight chamber or a draft so that harmful ozone gas does not pollute the ambient air. Since the treatment is performed at room temperature, vaporization of the organic solvent is relatively small, but contamination of the outside world due to the vaporization can be prevented at the same time. The exhaust pipe from the hermetic chamber is connected to an ozone decomposer utilizing ultraviolet irradiation of a wavelength of 253.7 nm or alkali solution treatment. If a cooling mechanism is provided in the exhaust system, the organic solvent can be liquefied and recovered. When acetic acid is used, it easily freezes, so that a high recovery rate can be obtained. Therefore, the present invention can be implemented with almost no pollution of the environment.
[0026]
When the wafer is placed in a carrier and immersed in ozone-containing acetic acid for the resist removal treatment according to the present invention, the effect of the carrier as in the case of immersion in ozone water is small because the resist removal rate is high, and the resist is uniformly removed to the periphery. I can do it. However, in the case of the immersion treatment, the treatment liquid is repeatedly used. Therefore, if the treated wafer is immediately placed in a pure water rinsing bath, a dissolved substance precipitates on the wafer surface and conversely causes contamination. Therefore, an acetic acid rinsing tank is required, and the amount of the chemical in the apparatus becomes too large.
[0027]
In the treatment with the liquid film of the present invention, the ozone concentration is high even if the amount of the liquid is small, so that the reaction to the contaminant is fast, and the contaminant dissolved by the movement of the liquid is separated from the object over time, so that the immersion is performed. The removal capacity is higher than the method. The movement of the liquid in the form of a film utilizes the spreading from the center by flowing down or centrifugal force. As for the moving speed of the liquid, it is sufficient that the supply amount is about 1 to 3 mL per minute for a 6-inch wafer. The apparatus can be configured in the same manner as an ordinary spray cleaning apparatus, single wafer spin cleaning apparatus, or steam cleaning apparatus.
In order to quickly increase and maintain the ozone concentration in the liquid film processing which is a feature of the present invention, an ozone gas introduction port and an exhaust port are provided in the chamber of these apparatuses, and the chamber is filled with the ozone gas. It is effective to do so, which is a feature of the present invention. However, when using a high-concentration ozone gas having an ozone concentration exceeding 200 mg / L, it is not necessary to introduce the ozone gas into the chamber.
[0028]
【Example】
The ozone gas used in the following examples has an ozone concentration of about 200 mg / L obtained by flowing 0.5% to 2 L / minute of oxygen containing 1% nitrogen into a small discharge type ozone generator. As acetic acid for absorbing ozone gas, 99% purity (remaining water) was used. (4) The photoresist film subjected to the removal treatment in each embodiment has a thickness of 800 nm and 1.5 μm on a p-type silicon wafer provided with a 100 nm oxide film. The processing for forming the resist film was performed by a standard procedure using a coating apparatus that is used in a normal LSI process. First, HMDS was applied, treated at 100 ° C. for 1 minute including evacuation, cooled to room temperature, and then a novolak resin-based resist was applied in the above thickness. The baking was performed at 140 ° C. for 1 minute for the thin resist film and 2 minutes at 90 ° C. for the thick resist film, and the latter was also prepared with a high dose ion-implanted sample.
[0029]
In an advanced VLSI, the amount of organic matter remaining after resist removal is extremely small (2 × 10^ThirteenAtom / cm²Since the following is desired, the amount of organic substances remaining on the silicon oxide film after the resist is stripped in this embodiment can be determined by a highly sensitive charged particle activation analysis method disclosed in Japanese Patent Application No. 10-253346. The absolute amount of surface organic carbon was determined.
[0030]
The cleaning effect on organic contamination on the silicon wafer in the present invention was confirmed by the same charged particle activation analysis that the residual organic carbon concentration after cleaning was sufficiently reduced by using a sample that was intentionally strongly contaminated with organic. It is also known that most of the pollutants that contaminate silicon wafers in clean rooms of semiconductor factories are DOP,¹⁴A DOP labeled with C was synthesized, and a silicon wafer that was intentionally contaminated with this was used. The remaining amount after washing was determined by measuring radioactivity by radioluminography using an imaging plate.
[0031]
Further, when the contaminants adhering to the flat surface are oils and fats or HMDS, the contact angle of the water droplet is increased. Therefore, the effect of removing such contaminants was also determined by whether the contact angle of the water droplet was reduced to about several degrees.
[0032]
[Example 1]
FIG. 1 shows a conceptual diagram of an apparatus for immersing a plurality of wafers with a photoresist film in a carrier in an ozone acetic acid solution to remove the films. The draft made for the experiment is divided into a front room 1, a processing room 2, and a rear room 3, and there is a glass door on the whole surface. However, the inside of the draft is isolated from the outside during operation, and all operations are performed outside. You. An atmosphere containing ozone and acetic acid in the processing chamber is provided in the front and rear chambers so that the quartz glass carrier 5 containing seven wafers 4 can be put into the processing chamber from the front chamber and can be taken out through the rear chamber after processing. And a door 6 that can be opened and closed with an air displacement mechanism (not shown) to prevent the air from leaking out of the draft.
[0033]
The quartz glass tank 7 is a tank for performing ozone treatment in acetic acid, and the quartz glass tank 8 is an acetic acid rinse tank. The quartz glass tank 9 is an overflow rinsing tank, and ultrapure water is supplied and drained through an inlet pipe 11 having a valve 10 and a drain pipe 12.
[0034]
Acetic acid is supplied to the rinsing tank from an inlet pipe 14 having a valve 13, and the acetic acid filled in the rinsing tank enters the ozone treatment tank 7 through a conduit 15. Acetic acid that has undergone wafer processing is gradually discharged to a drain tank through a drain pipe 17 having a valve 16. The amount of the processing solution in each tank is about 5 L.
[0035]
Ozone gas is introduced into the ozone treatment tank through a quartz glass tube 18, and the tip 19 of the tube is arranged at the bottom of the tank, and is provided with a large number of fine holes for gas diffusion. When ozone gas was supplied at 2 L / min, the ozone concentration in acetic acid reached 200 ppm or more in 5 minutes.
[0036]
A carrier on which a wafer with a resist film of 800 nm was set was attached to the robot arm 20 in the front chamber, immersed in an ozone acetic acid bath having an ozone concentration of 200 ppm or more for 1 minute, then rinsed in an acetic acid rinse bath for 1 minute, and placed on the rinse bath for 30 seconds. When the acetic acid drops were allowed to fall and the wafer surface reached a state where the wafer surface was covered with a thin acetic acid film, it was transferred to an ultrapure water tank and overflow rinsed for 3 minutes, and the carrier was taken out in the rear chamber. When the wafer was spin-dried and inspected with the naked eye, no resist remained on the entire surface.
[0037]
The wafer was cut into 2 cm × 2 cm chips and charged particle activation analysis revealed that the surface organic carbon concentration was 4 × 10¹⁴Atom / cm²It became. Although the resist has been removed, there is a possibility that a part of the methyl silicon layer may remain in addition to the adsorption of acetic acid molecules. However, this ozone acetic acid treatment has a stripping ability of 800 nm / min or more, that is, a strong stripping ability of one digit or more by the ozone water treatment with respect to the novolak resin-based resist.
[0038]
Acetic acid vapor and ozone gas generated in the draft are exhausted from the exhaust port 21 by a fan, and are exhausted as shown in the conceptual diagram of FIG. When the ozone concentration in the acetic acid in the tank 7 exceeds 100 ppm, the blue-violet color due to ozone becomes vivid. Since the color density has a positive correlation with the ozone concentration, the light source 22 and the light receiving unit 23 measure the absorbance at a wavelength of 595 nm, and when the ozone concentration reaches a predetermined value, the supply of ozone gas is stopped. Ozone emissions can be controlled to a minimum.
[0039]
The exhaust pipe 24 following the exhaust port terminates in a freezing chamber 26 with an outlet pipe 25. The freezing chamber is housed in a heat exchanger 27 capable of heating as well as cooling. The outlet pipe projects into a sealed pipe 30 to which the acetic acid recovery tank 28 can be attached and detached and to which an ozone exhaust pipe 29 is attached. A blower 31 was connected to the ozone exhaust pipe, and the atmosphere in the sealed draft was exhausted by the blower during the operation of this embodiment. At this time, the inside of the freezing room is lowered to 10 ° C. or less by operating the heat exchanger, and acetic acid in the exhaust is frozen in the room. After a series of operations, the frozen acetic acid is heated and melted and collected in a tank.
[0040]
The exhaust gas that has passed through the blower is introduced into a 253.7-nm UV irradiator using a low-pressure mercury lamp, and decomposes ozone and a small amount of acetic acid. In this example, no ozone odor or acetic acid odor was felt in the atmosphere outside the draft.
[0041]
[Example 2]
Since the residual amount of organic carbon was slightly large in one minute of ozone acetic acid immersion in Example 1, the treatment was similarly performed at an ozone concentration of 200 ppm or more with immersion for 10 minutes. A wafer in which a high dose ion implantation was performed on a 1.5 μm resist film was also used, and a wafer without resist coating was added to the following six types of samples as a control and set on a carrier. The pure water rinse was treated for 10 minutes by exchanging a 1 MHz ultrasonic vibrator with an overflow rinse tank attached to the lower part in order to remove acetic acid molecules adsorbed on the surface.
(1) 800nm resist film wafer
(2) 1.5 μm resist film wafer
(3) Dose amount 1 × 10 at 30 KeV¹⁴/ Cm²Of B⁺ウ ェ ー ハ Ion-implanted wafer
(4) Wafer subjected to 1 μm ashing in (3)
(5) A dose of 1 × 10 at 30 KeV^Fifteen/ Cm²Of B⁺ウ ェ ー ハ Ion-implanted wafer
(6) Wafer subjected to 1 μm ashing in (5)
1 × 10 of (5) with processed wafer^Fifteen/ Cm²Only the resist clearly remained, except for the naked eye. However, the surface dust count was 1 × 10^Fifteen/ Cm²Since the contamination by the desorption resist from the ion-implanted resist film was remarkable, the treatment was again performed except for the sample (5), and the number of fine particles having a size of 0.2 μm or more was 15 or less. As a result of the charged particle activation analysis, the amount of organic carbon was all (7 to 10) × 10^ThirteenAtom / cm²And 1 × 10¹⁴/ Cm²It is presumed that the resist including that of the ion implantation was completely removed, and that the methyl silicon layer was also largely removed.
NH for these wafers₄OH: H₂O₂: H₂When O = 1 volume: 1 volume: 12 volume SC-1 washing was followed, the amount of residual organic carbon was (4-7) × 10 in all samples.¹²Atom / cm²The methyl silicon layer and the adsorbed acetic acid were completely removed.
[0042]
[Example 3]
Since ozone acetic acid has a large resist dissolving ability, ozone acetic acid was supplied to the wafer by a spray nozzle 32 as shown in FIG. 3, and an attempt was made to remove the resist by flowing down the liquid film. In a chamber 34 covered with a lid 33 that can be moved up and down, there are an inlet pipe 36 and an ozone gas outlet pipe 37 through which ozone gas can be supplied by a valve 35, and a table 39 on which the carrier 5 on which the wafer 4 is set is slightly rocked by a shaft 38. It has been incorporated. The valve 40 is located in the treated acetic acid discharge pipe 41 and is closed during the treatment, and is discharged after the treatment. Ozone gas is introduced into the chamber at a rate of 2 L / min, the carrier is rocked, and ozone acetic acid is dropped onto the wafer from the spray nozzle located on the wafer. Spraying is first performed until the entire surface of the wafer becomes wet, and thereafter, intermittently performed so that ozone acetic acid drops from the lower end of each wafer.
[0043]
Spraying of ozone acetic acid is performed by feeding ozone acetic acid in the absorption container 42 having an impinger structure into the spray pipe 45 at a pressure of nitrogen through the electromagnetic valve 44 by the three-way cock 43. Ozone acetic acid was prepared by sending ozone gas at a rate of 1 L / min to acetic acid in a 500 mL container through a valve 46 and a perforated nozzle 48 via a valve 46 in advance to absorb ozone. This acetic acid was introduced through the introduction pipe 49 and the valve 50.
[0044]
The resist was stripped except for the sample (5) shown in Example 2. The spraying treatment was performed for 10 minutes including the intermittent stop time, with a spray liquid amount of 20 cc per one sheet. Thereafter, only nitrogen-containing oxygen was flowed from the introduction tube 36 to dry the acetic acid on the wafer. When these were subjected to SC-1 cleaning in the same manner as in Example 2, the residual organic carbon amount was all (3 to 7) × 10¹²Atom / cm²The number of particles of 0.16 μm or more was 10 or less for each wafer. When the same treatment was performed with propionic acid instead of acetic acid, the residual carbon amount was not significantly different from that of acetic acid.
[0045]
[Example 4]
Sample (5) of Example 2, that is, 1 × 10^FifteenOzone acetic acid spraying treatment was performed on the ion-implanted resist in the same manner as in Example 3. However, hydrofluoric acid (49% by weight) was added in a ratio of 1/200 to acetic acid. In the case of intermittent spraying of 20 cc per sheet for 10 minutes, the resist could hardly be removed, but it was clearly embrittled. When the wafer was subjected to high-pressure jet spray of ultrapure water and spin-dried, the contact angle of a water droplet on the oxide film surface was 5 ° or less. On the other hand, when SC-1 cleaning was performed, the residual organic carbon amount was 6 × 10¹²Atom / cm²As a result, the high dose ion-implanted resist could be removed.
[0046]
[Example 5]
For each of the four oxidized wafers having the same specifications as those used in each of the above embodiments,²²7 × 10 Na labeled with Na¹¹Atom / cm²,⁵⁷Ni labeled Ni 2 × 10¹¹Atom / cm²,⁵⁹5 × 10 Fe labeled with Fe¹¹Atom / cm²,⁶⁴5 × 10 Cu labeled with Cu¹¹Atom / cm²Made intentional pollution. For this contamination, chlorides of the respective elements were adhered to the wafer surface so as to be substantially uniform by an evaporation method devised with an aqueous solution, and dehydrated at 140 ° C. Thereafter, HMDS coating treatment was performed to examine the metal contamination removal ability of the treatment with hydrofluoric acid and ozone acetic acid when there was strong organic contamination.
[0047]
Spraying was performed with hydrofluoric acid-containing ozone acetic acid in the same manner as in Example 4 and stopped in 3 minutes as in Example 3, and the carrier was rinsed with ultrapure water for 1 minute using a spin dryer with pure water rinse. The water droplet contact angle was 4 ° or less in all wafers, and it was found that the methyl silicon layer due to HMDS was substantially removed. In addition, each element was measured as 3 × 10⁹Atom / cm²In the following, it was found that this treatment was also effective for removing metal contamination.
[0048]
[Example 6]
A wafer having the same specifications as those used in each of the above embodiments was immersed in hydrofluoric acid to remove an oxide film, and γ-rays were emitted from dilute hydrofluoric acid with a half-life of 12.8 hours to the back surface (etched upper surface). Do⁶⁴1 × 10 Cu labeled with Cu¹¹Atom / cm²Adsorbs and emits only beta rays with a very long half-life on the back surface¹⁴1 × 10 DOP labeled with C¹⁴Molecule (2.4 × 10^FifteenCarbon atom) / cm²Attached. The sample was subjected to hydrofluoric acid-containing ozone acetic acid treatment and pure water rinse and drying in the same manner as in Example 5 to measure γ-rays. As a result, the residual amount of Cu was 2 × 10⁹Atom / cm²Met. Also⁶⁴One week after the disappearance of β-rays from Cu, β-rays were measured to determine the residual amount of DOP.¹²Atom / cm²Met. Therefore, the ozone acetic acid treatment is sufficiently effective in removing contaminants such as organic substances and metals attached to the back surface.
[0049]
[Example 7]
A single-wafer spin ozone acetic acid treatment apparatus as shown in FIG. 4 was prepared by modifying a single-wafer cleaning machine capable of spin cleaning, spin rinsing and spin drying of diluted hydrofluoric acid. A low-pressure mercury lamp 54 was incorporated in a lid 53 of a chamber 52 having a spin axis 51. Three C-200UZs were used in parallel. A part of the lid was made of a synthetic quartz glass plate 57 so that the 184.9 nm ultraviolet light of the mercury lamp could reach the surface of the processing target wafer 56 held by the support 55 without loss. The chamber 52 has an ozone gas introduction pipe 59 and a discharge pipe 60 supplied by a valve 58, an acetic acid introduction pipe 61 which rotates only during the ozone acetic acid treatment and drops acetic acid or ozone acetic acid at the center of the wafer, and an ultrapure water after the treatment. An ultrapure water introduction pipe 62 for rinsing is attached. Inflow is made by valves 63 and 64, respectively.
[0050]
With respect to the sample (1) of the 800 nm resist film shown in Example 2 and the sample (4) ashed after ion implantation, the resist was peeled off by this apparatus. In each case, the rotational speed of the wafer was 100 rpm, and ozone gas having an ozone concentration of 200 mg / L was supplied at 2 L / min. 200 ppm or more of ozone acetic acid prepared in an ozone absorption container similar to that shown in Example 3 was introduced into the center from the acetic acid introduction pipe 61, and about 80 drops were dropped in one minute when the entire surface of the wafer was wet. Thereafter, ultrapure water was flowed in for 20 seconds to carry out spin rinsing, introduction of ozone was stopped, and the wafer was spin-dried at 4000 rpm, and then irradiated with ultraviolet rays at 100 rpm for 1 minute. As a result of charged particle activation analysis of the wafer, residual organic carbon was 3 and 5 × 10¹²Atom / cm²As a result, both the resist and the methyl silicon layer were sufficiently removed.
[0051]
Example 8
In the apparatus of FIG. 4 used in the previous embodiment, a low-pressure mercury lamp was not provided for the chamber lid 53, and the chamber lid 53 was simply provided with the function of a lid. On the other hand, a dilute hydrofluoric acid introduction pipe similar to the ultrapure water introduction pipe 62 was added. The sample (1) of the 800 nm resist film shown in Example 2 was treated with ozone acetic acid and rinsed with pure water in the same manner as in the previous example, and then rinsed with diluted hydrofluoric acid (hydrofluoric acid: water-1 volume: 50 volumes). For 15 seconds and rinsing with pure water for 15 seconds, followed by spin drying as in the previous example. The residual carbon amount is 1 × 10^ThirteenAtom / cm²In this case, the adsorbed molecules can be removed sufficiently, although the level is slightly higher than that of the previous embodiment, which can be practically used in device production.
[0052]
[Example 9]
SC-1 processing was performed on the wafer from which the oxide film had been removed as in Example 6.¹⁴C-labeled DOP is dissolved in hexane and applied over the entire surface, and the hexane is rapidly evaporated to a DOP concentration of 1 × 10¹⁴Molecule / cm²Intentionally contaminated samples were prepared.
Using the apparatus of Example 7, propionic acid having a purity of 99% was introduced from the introduction pipe 61, and treatment for one minute and pure water rinsing / ultraviolet irradiation were performed in the same manner as in Example 7. However, the number of rotations of the wafer was 50 rpm, and the amount of dripping after the wafer was wet was 50 drops. When the radioactivity was measured after the treatment, the residual DOP was 2 × 10¹¹Molecule (5 × 10¹²Carbon atom / cm²), DOP was sufficiently removed.
[0053]
[Example 10]
An embodiment in which the liquid film processing according to the present invention is performed by a steam cleaning mechanism will be described with reference to FIG. A lid 65 which can be moved up and down, a heater 67 for storing a dichloromethane solution in a bottom portion 66 and heating and evaporating the solution, and a cooling pipe 70 for cooling a plate-like glass object 69 containing a carrier 68 set above the solution. This device is constituted by the chamber 71 equipped with. The feature of this device is that an ozone gas introduction pipe 73 having a valve 72 and an ozone gas exhaust pipe 74 are provided. The leading end of the introduction pipe is connected to a perforated pipe 75 for generating a fine gas of ozone and dichloromethane by generating fine bubbles of ozone gas in the liquid. The device was made of stainless steel plates and tubes.
[0054]
A glass plate coated with a pitch for lens polishing is set on a carrier as a deliberately contaminated sample, and a steam cleaning of dichloromethane is performed while flowing ozone gas having a concentration of about 200 mg / L at a flow rate of 2 L / min. did. All were finished in a dry state in 10 minutes, and the contact angle of the water droplet was measured. From 30 to 35 ° when ozone was not used, the angle was reduced to about 10 ° or less. After that, ultraviolet irradiation with C-200UZ was performed for 2 minutes, and the contact angle of water droplets became 3 °. In the case of a cleaning product using only dichloromethane, ultraviolet irradiation took 20 minutes or more to obtain this angle.
[0055]
[Example 11]
An iron plate required to remove oily dirt was set as a pretreatment for plating on the carrier of Example 9 and subjected to steam cleaning and ultraviolet light treatment for 2 minutes in the same manner as in Example 9, and the contact angle of water droplets was 55 ° before cleaning. From 4 °.
[0056]
[Example 12]
An ozone generator capable of obtaining high concentration ozone of 200 mg / L to 300 mg / L at a flow rate of 0.5 to 1 L / min was prepared. A quartz glass filter having a nozzle end at a nozzle end is filled with a acetic acid obtained by adding water to a quartz glass impinger (volume: 100 mL) at a different ratio, and a 1% nitrogen-containing oxygen gas containing 220 mg / L of ozone produced by the generator is supplied. Bubbling was performed, and after 5 minutes, the concentration of ozone dissolved in the liquid was measured assuming that ozone was saturated. The quantitative method is a volumetric analysis method using a reaction in which potassium iodide is converted to iodine by ozone. The dotted line in FIG. 6 shows the relationship between the acetic acid concentration of the hydrous acetic acid and the obtained saturated ozone concentration (the liquid temperature is 20 ° C.).
[0057]
The solid line in FIG. 6 shows the relationship between the acetic acid concentration of the ozone-saturated aqueous acetic acid and the stripping rate of the ozone-saturated acetic acid with respect to the novolak resin-based resist IX555 (manufactured by JSR Corporation). An experiment to determine this relationship was performed as follows.
The above-mentioned IX555 was applied to a thickness of 1.5 μm on the 100 nm oxide film wafer that had been subjected to the HMDS coating treatment as described above, and baked at 140 ° C. for 60 seconds to form a 2 cm × 2 cm square sample. The resist was cut, and at the bottom of a small quartz beaker, 10 mL of the above-mentioned ozone-saturated acetic acid was added.
From this figure, it can be seen that when 220 mg / L ozone gas is used, the ozone saturation amount is 380 mg / L, and the stripping rate of acetic acid having a purity of 98% or more to the novolak resin-based resist IX555 reaches 6 μm / min or more. In the present invention, when the ozone concentration in acetic acid approaches 400 mg / L, a resist film having a thickness of 1.5 μm can be removed in a very short time of about 15 seconds.
[0058]
[Example 13]
If the concentration of ozone gas is increased as in the previous example and a glass filter is used to emit ozone, acetic acid with a high concentration of about 400 ppm of ozone can be easily obtained, and the novolak resin-based resist can be removed by contact for 30 seconds or less. For such treatment with acetic acid having a high ozone concentration, it can be said that the use of a single wafer spin cleaning mechanism is preferable. Therefore, a resist removing apparatus having a cross-sectional view shown in FIG. 7 was prepared using the single wafer spin cleaning mechanism of Example 7.
[0059]
The wafer 55 to be processed in the single-wafer spin processing is configured such that the support 55 is rotated by a rotation mechanism 76 by a spin rotation shaft 51 so as to spin. being surrounded. This single-wafer processing mechanism, a support table 78 of a wafer cassette 77 for accommodating all of the wafers to be processed, and a transfer robot 79 for automatically taking in and out wafers between the cassette and the support 55 are provided with an explosion-proof type. It is provided in the housing 80. It should be noted that a mechanism for automatically opening a part 81 of the wall surface of the chamber when the wafer enters and exits is provided. A processing liquid supply pipe 83 terminated by a nozzle 82 for releasing ozone acetic acid and a acetic acid supply pipe 85 terminated by a nozzle 84 for releasing acetic acid for rinsing penetrate through the wall of the housing. are doing. Incidentally, these two supply pipes can be integrated into one by a valve operation.
[0060]
Further, the liquid is sent to a liquid discharge pipe 86 for discharging the acetic acid collected at the bottom of the chamber, a gas introduction pipe 87 for replacing the atmosphere in the housing, and an ozone decomposer (not shown) using a catalyst such as Mn. The ozone exhaust pipe 37 to be noticed penetrates the housing wall. The housing is provided with an openable / closable door 6 for taking a wafer cassette in and out, and opens and closes only when ozone and acetic acid are discharged from the atmosphere in the housing.
The ozone acetic acid solution can be prepared by sending ozone gas to the acetic acid 88 stored in the ozone absorbing container 42 to the ozone radiator 89 of the quartz glass filter through the pipe 59 through the valve 58. Normally, a saturated ozone concentration becomes almost attained by 5 minutes of ventilation. This liquid is supplied to the nozzle 82 through the supply pipe 83 for a predetermined time through a Teflon liquid supply pump indicated by P and a precision filter for dust indicated by F. The supply of acetic acid to the ozone absorbing container and the discharge from the container are performed by a pipe 91 having a valve 90. Acetic acid 92 for rinsing is supplied to another container 93 via a pipe 95 having a valve 94. The rinsing liquid is sent to the rinsing nozzle 84 for a predetermined time by a pipe 85 passing through a liquid sending pump and a precision filter for dust.
[0061]
HMDS was applied to a 6 ″ wafer of 100 nm oxide film as described above to form a 1.5 μm film of photoresist IX555, and baked at 140 ° C. for 60 seconds to prepare 25 sheets, and a cassette as shown in FIG. And set it.
About 300 mL of acetic acid is put into the ozone absorption container 42, and nitrogen-containing oxygen having an ozone concentration of 220 mg / L is bubbled from the ozone diffuser at a flow rate of 1 L / min to reach a maximum concentration of 380 mg / L in about 5 minutes. . When the wafer 56 was rotated at 1000 rpm and ozone acetic acid was discharged from the nozzle 82 at a rate of 1.5 mL / sec, the entire surface of the resist was removed in 15 seconds with the naked eye. The acetic acid in the acetic acid container 93 was rinsed from the nozzle 84 at a rate of 1.5 mL / sec for 10 seconds, and the rotation of the wafer was increased to 4000 rpm and spin-dried for 30 seconds. The wafer was replaced with a wafer in the cassette and processed continuously for 25 wafers. However, despite the fact that the resist decomposition residue in the ozone absorbing container should have accumulated, the time required for the visual stripping of about 15 seconds did not change to the end.
[0062]
Remove the cassette from which all wafers have been removed from the housing, rinse with ultra-pure water overflow for 10 minutes using a normal cleaning device, spin dry, cut out 2 cm x 2 cm square chips from these wafers, and emit charged particles. Analysis of the amount of residual organic carbon by chemical analysis (0.8-2.6) × 10^ThirteenAtom / cm²It was found that not only the resist but also the HMDS film was almost completely removed.
The reason why the processing solution is not deteriorated is that when the waste ozone acetic acid solution after the single wafer processing returns to the ozone saturated container, high concentration ozone is always present, so that the dissolved resist is strongly decomposed. It is considered that the purification proceeds to a purity level sufficient for reuse, while acetic acid hardly changes even at a high concentration of ozone. That is, in this treatment method, the treatment solution can be circulated and reused, and it can be said that newly required acetic acid is only used for rinsing. Since the amount of liquid in the absorption container increases, the rinse liquid is gradually discharged by the valve 90. However, since the acetic acid purity of the discharge is high, it can be recovered at an extremely high recovery rate by distillation, and can be used for rinsing.
[0063]
[Example 14]
The technegas device used for medical diagnosis of the respiratory system is a device that creates an argon atmosphere in which ultrafine carbon dust of 0.1 μm or less is dispersed. These fine particles have a half-life of 6 hours.^99mLabeled with Tc. Using this apparatus, the film surface of the wafer with the resist film used in the previous example was contaminated, and the radiation dose due to the attached carbon particles on the entire surface was determined by radioluminography using an imaging plate to be 2600 PSL / cm.²Had radioactivity. A single-wafer test apparatus dedicated to the radiation experiment was prepared, the resist was removed with an acetic acid solution having the same ozone concentration as in the previous experiment under the same stripping conditions, and after rinsing and drying of the acetate, the same radioluminography measurement was performed. Radiation dose based on residual carbon particles is 20 PSL / cm of background²It was below. This ozone acetic acid treatment was found to be effective for removing fine particles.
[0064]
[Example 15]
According to Henry's law, the ozone concentration of the ozone acetic acid solution also increases in proportion to the ozone concentration in the gas emitted in acetic acid. The relationship between the acetic acid concentration in the aqueous acetic acid and the saturated ozone concentration when the ozone concentration in oxygen was increased to 280 mg / L is shown by the broken line in FIG.
When the acetic acid concentration is reduced to 80% by volume, explosion-proofing of the device becomes unnecessary and there are many structural advantages. If the ozone concentration in the gas to be radiated is 280 mg / L even if the moisture is present, the ozone concentration in acetic acid will be 250 ppm, the stripping speed of the novolak resin resist will be about 1 μm / min, and single wafer spin processing will be possible. .
A novolak resin resist IQ2002 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) having a film thickness of 800 nm was used. The ozone concentration in oxygen was set to 280 mg / L, and acetic acid was set to 80% by volume (remaining water) in both containers. The experiment was performed in exactly the same manner as in Example 12, except that the time was changed to 1 minute.
The macroscopic resist stripping time was 45 seconds on average. When the residual organic carbon concentration was measured by treating in the same manner as in Example 12, all were 3 × 10^ThirteenAtom / cm²Below, most of the HMDS layer has also been removed. Furthermore, when SC-1 treatment was performed thereafter, the residual organic carbon concentration was 5 × 10¹²Atom / cm²In the following, a degree of cleanliness that could be said to be sufficient was obtained.
[0065]
【The invention's effect】
In a semiconductor lithography process, the positive resist on the oxide film is reduced to a residual organic carbon amount of 10 including the methyl silicon layer at the interface derived from the adhesive HMDS.^ThirteenAtom / cm²In order to remove to the following, in the conventional method, the piranha treatment whose composition is sufficiently controlled must be performed, and the SC-1 treatment must be followed. The piranha treatment requires a high temperature treatment of about 130 ° C.₂O₂Is disassembled into H₂In addition to the fact that the solution becomes O, the solution is diluted and the effect is reduced, and at that time, the sulfuric acid becomes a mist and scatters. Since the present invention requires ozone treatment, a closed system is required, but ozone gas in exhaust gas can be easily decomposed, and organic solvents such as acetic acid are treated at room temperature, so that the amount of scattering is small, and when acetic acid is used, the decomposition treatment must be performed. Can be recovered by cooling before. In the present invention, if the ozone acetic acid solution after the removal treatment is restored to an ozone dissolving (absorbing) solution for bubbling ozone, the ability to decompose ozone-treated contaminants such as a novolak resin-based resist is strong. In this case, the resin decomposes into glyoxal and glyoxylic acid through muconic acid and the like via maleic acid and the like, and the photosensitizer naphthoquinone azide through phthalic acid and the like, and finally from formic acid into water and carbon dioxide. That is, purification is performed in the process of ozone bubbling, and acetic acid is used for a long life. In short, the organic solvent is purified with ozone, and the amount of the organic solvent used is extremely small as compared with the case where the other resist remover that merely dissolves accumulates and dissolves, resulting in an effect that is economically excellent. Therefore, in the present invention, both ozone and such an organic solvent can easily take measures against environmental pollution. In particular, acetic acid is very safe because of its very low toxicity.
[0066]
In addition, compared with piranha treatment and conventional ozone treatment, the treatment method of the present invention has a stripping speed for such a resist one to two orders of magnitude higher. This is because the organic solvents used in the present invention have an ozone solubility of about 10 times that of water, and these organic solvents are not easily decomposed by ozone. In addition, since these organic solvents have a small surface tension and easily spread on the surface of the object, the surface of the object can be efficiently treated with the organic solvent liquid film having a high ozone concentration. Therefore, the processing can be performed with a small amount of liquid, and the liquid film processing is performed in an ozone atmosphere in order to keep the ozone concentration in the liquid film as high as possible, so that the amount of ozone gas used is smaller than in the case of ozone water processing.
[0067]
Since the positive resist stripping ability of the present invention is extremely strong, 1 × 10¹⁴/ Cm²B⁺Ion-implanted resist dissolves easily, 1 × 10^Fifteen/ Cm²Even with the implanted resist, a chemical action (brittleness) that could be sufficiently removed by high-pressure jet spray cleaning later could be given. The resist in which the ion-implanted layer has been ashed can be removed by a single-wafer single-wafer ozone acetic acid liquid film treatment. In addition, since the surface tension of the liquid is small, in the device manufacturing process having a fine pattern, the resist removing effect can be easily provided to every corner of the pattern, and fine particles can be removed well. In addition, since the acid treatment with strong oxidizing power by high concentration ozone is effective in removing various contaminants such as removal of metal contamination, it also has an advantage as a cleaning agent.
[0068]
Carboxylic acid molecules such as acetic acid adsorbed in the treatment of the present invention are ionized during the subsequent pure water rinse. These ionized molecules are easily oxidized. For example, ultraviolet ozone treatment decomposes and disappears in a very short time, and the same applies to alkali-hydrogen peroxide treatment.¹²Atom / cm²Has a cleaning effect of reaching the order of
[0069]
The effect of the moving liquid film treatment of an ozone organic solvent in an ozone atmosphere according to the present invention can be easily applied to steam cleaning of dichloromethane having high ozone solubility, low surface tension and relatively low toxicity. This treatment, in combination with the short-time ultraviolet ozone treatment, has the effect of simplifying the advanced removal of contaminants such as organic substances when adhesion of water is not desirable.
[0070]
[Brief description of the drawings]
FIG. 1 is a conceptual diagram in a case where the present invention is performed by immersion of a processing object.
FIG. 2 is a conceptual diagram relating to treatment of an ozone exhaust gas containing acetic acid.
FIG. 3 is a longitudinal sectional view of a liquid film falling-down processing apparatus using an ozone acetic acid liquid spray according to the present invention.
FIG. 4 is a longitudinal sectional view of a single-wafer liquid film transfer processing apparatus using ozone acetic acid droplets according to the present invention.
FIG. 5 is a longitudinal sectional view of a dichloromethane vapor cleaning apparatus in an ozone atmosphere according to the present invention.
FIG. 6 shows the relationship between the acetic acid concentration of hydrous acetic acid and the saturated ozone concentration obtained in Example 12 (dotted line: ozone concentration 220 ppm, dashed line: ozone concentration 280 ppm), and the acetic acid concentration of ozone saturated acetic acid and novolak resin. The relationship (solid line) with the stripping rate for the system resist is shown.
FIG. 7 is a conceptual diagram illustrating a resist removing apparatus according to the present invention.
[Explanation of symbols]
1. Pre-draft room 2. Draft processing room 3. Draft rear room
4. Target wafer # 5. Wafer carrier $ 6. Door that can be opened and closed
7. Ozone acetic acid treatment tank $ 8. Acetate rinse tank # 9. Pure water rinsing tank
10. Pure water valve # 11. Inlet pipe for pure water # 12. Water pipe for pure water
13. Acetic acid valve # 14. Inlet tube for acetic acid # 15. Acetic acid conduit
16. Drain pipe valve # 17. Drain pipe # 18. Ozone gas inlet pipe
19. Ozone emission tube $ 20. Robot arm for carrier movement
21. Draft exhaust port # 22. Ozone colorimetric light source # 23. Ozone colorimetric receiver
24. Exhaust pipe # 25. Dissolved acetic acid outlet pipe # 26. Acetic acid freezing room
27. Heat exchanger for cold heat # 28. Acetic acid recovery tank # 29. Ozone exhaust pipe
30. Tank cap sealed tube # 31. Blower # 32. Ozone acetic acid spray nozzle
33. Chamber lid # 34. Chamber # 35. Ozone gas valve
36. Ozone gas inlet pipe $ 37. Ozone gas discharge pipe # 38. Carrier swing axis
39. Carrier swing table # 40. Acetic acid discharge valve # 41. Acetic acid discharge pipe
42. Ozone absorption container {43.3 side cock} 44. Solenoid valve for nitrogen pressure feed
45. Ozone acetic acid spray tube # 46. Ozone gas valve 47. Ozone gas inlet pipe
48. Ozone gas emission nozzle 49. Acetic acid introduction tube # 50. Acetic acid valve
51. Spin washing machine spin axis 52. Chamber # 53. Chamber lid
54. Low pressure mercury lamp # 55. Wafer support tool # 56. Wafer to be processed
57. Synthetic quartz glass plate # 58. Ozone gas valve 59. Ozone gas inlet pipe
60. Ozone gas discharge pipe # 61. Acetic acid introduction tube {62. Pure water inlet pipe
63. Acetic acid valve # 64. Pure water valve $ 65. Chamber lid
66. Dichloromethane reservoir {67. Heater # 68. Workpiece carrier
69. Plate-shaped object {70. Cooling pipe # 71. Chamber
72. Ozone gas valve # 73. Ozone gas inlet pipe # 74. Ozone gas discharge pipe
75. Ozone gas emission tube # 76. Rotation mechanism # 77. Wafer cassette
78. Support base # 79. Transfer robot # 80. Housing
82. Nozzle # 83. Processing liquid supply pipe # 84. nozzle
85. Acetic acid supply pipe # 86. Liquid discharge pipe {87. Gas inlet pipe
88. Acetic acid 89. Ozone diffuser $ 90. valve
91. Piping # 92. Acetic acid for rinsing

Claims (15)

A treatment liquid in which ozone is dissolved in an organic solvent having a distribution coefficient of 0.6 or more in ozone at 100 ppm or more is brought into contact with the surface of the treatment object to which contaminants are attached, and the surface of the treatment object is adhered. A method for removing contaminants adhering to a surface, comprising removing contaminants. By forming a liquid film of the processing liquid on the surface of the processing object to which the contaminant adheres, and continuously or intermittently supplying a new processing liquid to the liquid film to move the liquid film, 2. The method for removing contaminants adhering to a surface according to claim 1, wherein the surface of the treated body is brought into contact with an ozone-containing treatment liquid. In an atmosphere containing ozone, a liquid film of the organic solvent is formed on the surface of the object to which the contaminant is attached, and the solvent is continuously or intermittently supplied with a new solvent to the liquid film. The method for removing contaminants adhering to a surface according to claim 1, wherein the surface of the object to be treated is brought into contact with the ozone-containing treatment liquid by moving the surface. 4. The method according to claim 2, wherein the supply of the treatment liquid or the organic solvent is performed by spraying. 4. The method according to claim 3, wherein the supply of the organic solvent liquid is performed by condensing vapor generated from the heated liquid on the cooled surface of the object. The organic solvent has the _{formula: C n H 2n + 1 (} COOH) surface according to any one of claims 1 to 5, characterized in that a fatty acid represented by [n = 1, 2 or 3 of the integer How to remove adhering contaminants. The method according to claim 6, wherein water containing 5% by volume or less of an inorganic acid is added to the organic solvent composed of the fatty acid. 7. The method according to claim 6, wherein the organic solvent comprising the fatty acid contains 15 to 30% by volume of water. The method according to any one of claims 1 to 5, wherein the organic solvent is dichloromethane. A chamber having an inlet and an outlet for a gas containing ozone, and an organic solvent having a distribution coefficient of ozone in the gas of 0.6 or more over the entire processing surface of the object to be processed held in the chamber. And a mechanism for forming a liquid film in which is dissolved 100 ppm or more and moving the liquid of the film. 11. The processing object according to claim 10, wherein the mechanism for forming the liquid film is a sprayer provided above or to the side of the processing object held in the chamber and operated continuously or intermittently. A device for removing contaminants adhering to the body surface. A mechanism for forming a liquid film of the organic solvent on the surface of the object to be processed and moving the film-like liquid is provided by the organic solvent reservoir provided below the object to be processed held in the chamber and heating the liquid. The apparatus for removing contaminants adhering to a surface of an object to be processed according to claim 10, wherein the apparatus is a steam cleaning mechanism including a vessel and a cooler provided on a side of the object to be processed. A mechanism for forming a liquid film of a processing liquid in which ozone is dissolved in an organic solvent having a distribution coefficient of 0.6 or more in a gas with ozone in a gas of 0.6 or more on the surface of the object to be processed and moving the film-like liquid, Removal of contaminants adhering to the surface of the plate-shaped object to be processed, comprising a mechanism for rotating the plate-shaped object to be processed in a chamber while holding the plate substantially horizontally and a mechanism for discharging the solvent to the plate surface. apparatus. A mechanism for supplying a fixed amount of a processing liquid comprising a fatty acid represented by the formula: C _n H _{2n + 1} (COOH) [n = 1, 2, or 3] in which ozone is dissolved in an amount of 100 ppm or more, and a supply liquid transport pipe A chamber having a front end nozzle, a waste liquid discharge pipe and an exhaust gas introduction pipe, a discharge pipe thereof, and an openable and closable doorway for entering and exiting the workpiece, and rotating the workpiece plate in the chamber to form the nozzle. An apparatus for removing contaminants adhering to the surface of a plate-shaped workpiece, comprising: a mechanism for forming a liquid film by centrifugal force of the liquid supplied from the apparatus; and a transport mechanism for transporting the workpiece. Ozone 150ppm or more, including 200ppm or more dissolved vital 15 to 30 volume percent water as needed, _wherein: a constant _{C n H 2n + 1 (COOH} ) [n = 1,2 or 3 integer represented by fatty acid A chamber for supplying a quantity, a tip nozzle of the supply liquid transport pipe, a waste liquid discharge pipe, an exhaust gas introduction pipe, and a discharge pipe and an openable and closable doorway for entering and exiting the object to be processed; A plate-shaped object to be processed, comprising: a mechanism for rotating an object to be processed in a chamber to form a liquid film by centrifugal force of a liquid supplied from the nozzle, and a transport mechanism for the object to be processed. A device for removing contaminants adhering to the surface.

Images